We consider a smooth fibration equipped with a flat complex vector bundle and
a hypersurface cutting the fibration into two pieces. Our main result is a
gluing formula relating the Bismut-Lott analytic torsion form of the whole
fibration to that of each piece. This result confirms a conjecture proposed in
a conference in Goettingen in 2003. Our approach combines an adiabatic limit
along the normal direction of the hypersurface and a Witten type deformation on
the flat vector bundle.Comment: 76 page